This invention relates generally to permanent magnet (PM) machines and more specifically to transverse flux machines.
Permanent magnet (PM) transverse flux machines (TFMs) conduct magnetic flux perpendicular (transverse) to the current in the coil and can produce higher torque density than standard PM brushless machines with longitudinal flux. TFMs are high power density machines and can be used both as motors and generators. Torque increases with the number of poles at a constant stator current. Due to the high number of poles in a TFM, the frequency of electric current in stator windings is high while shaft speed is low. This makes TFMs desirable in a variety of applications including: propulsion motors for land and sea vehicles, electric and hybrid electric vehicles, ship propulsion motors, underwater vehicles, torpedoes, propulsion motors for electric helicopters, elevator propulsion motors, wind generators, integrated starter/generators, and high frequency low speed machines.
TFMs have a three dimensional (3D) magnetic circuit which has traditionally made fabrication and assembly of stator and rotor components difficult. Prior art methods of manufacturing the magnetic circuits require the formation of individual U-shaped magnetic circuits. For example, a U-shaped magnetic circuit may be comprised of a plurality of individual U-shaped laminations stacked together. Assembly of the TFM then requires the correct placement, alignment and spacing of each U-shaped magnetic circuit. Another method known in the prior art is to construct two 3D stacks, each having one half of every magnetic circuit as a series of L-shaped protrusions. When joined together around the coil, the magnetic circuits are completed in the U-shape. This method requires the construction of a stack with a complex 3D shape and requires precise rotational alignment of the two stacks to properly form the magnetic circuits.
There is a need for TFM components that can be efficiently manufactured and assembled.